Mammalian cell cycle protein

ABSTRACT

A novel mammalian cell cycle protein, p55CDC, DNA sequences encoding p55CDC, and a method for producing the protein are described. Also described are methods for detecting p55CDC and methods for modulating cell division by compounds which control the level or activity of p55CDC or p55CDC-associated protein complexes.

This is a division of U.S. application Ser. No. 08/988,856, filed Dec. 11, 1997, U.S. Pat. No. 6,291,642, which is a continuation of U.S. application Ser. No. 08/448,864, filed May 24, 1995. abandoned, which is a division of U.S. application Ser. No. 08/195,730, filed Feb. 14, 1994, abandoned. U.S. Ser. No. 08/195,730 is hereby incorporated by reference herein for any purpose.

The invention relates to a mammalian cell cycle protein, p55CDC, DNA sequences encoding same, antibodies specific for the protein, a method for producing the protein and methods for modulating cell division by controlling the levels or activity of p55CDC or p55CDC-associated protein complexes.

BACKGROUND OF THE INVENTION

The eukaryotic cell cycle has a growth phase and a reproductive phase, the latter composed of the chromosome cycle and the centrosome cycle which intersect in the establishment of the mitotic apparatus (for review, see 47). The profound morphologic changes which result in mitosis are accompanied by a cascade of phosphorylation and dephosphorylation events. In mammalian cells, different complexes of kinases and their associated regulatory proteins control progression through discrete steps of the cell cycle (for review, see 60, 67). While all eukaryotic cells use similar mechanisms to regulate progression through the stages of the cell cycle, it is clear that unique combinations of regulatory cyclins, kinases and phosphatases are responsible for cell- and organism-specific patterns of cell division (18, 51, 52).

A variety of kinases have been identified which control the crucial transitions through the cell cycle. The most well characterized is the p34^(cdc2) protein, which has been identified in all eukaryotic cells which have been examined (3, 16, 20, 28, 40, 41, 42, 59, 76). In addition, many other kinases which have homology to p34^(cdc2) and, like p34^(cdc2) fluctuate in activity during the cell cycle, have been described (48, 60). Other types of kinases have also been shown to vary in activity at different stages of the cell cycle, and have been proposed to play a role in control of cell division, although they share little or no homology with p34^(cdc2). These include the MAP kinases, and the MEK kinases which regulate MAP kinase activity (for review, see 11). In addition, a novel kinase has been identified in the fungus Aspergillus nidulans, the NIMA kinase, which is required to initiate mitosis (53-55). A mammalian kinase, Nek1, which has homology to the NIMA kinase, has been found in mouse, where it is expressed at high levels in gonadal tissues and may be required for meiosis (43).

As mentioned above, the activity of many of these kinases is regulated by their association with one or more cyclins. The cyclins are homologous with one another within a conserved region termed the cyclin box (44). The fluctuations in activity of the cyclin dependent kinases during the cell cycle result from differential association with newly synthesized cyclins, which are then degraded at specific transition points in the cell cycle. However, not all cyclins demonstrate the same degree of fluctuation during the cell cycle; for example, levels of the D type cyclins do not oscillate as dramatically during the cell cycle as the A and B type cyclins. In addition, a recently described cyclin, the mcs2 cyclin of S. pombe, shows no variation in level during the cell cycle, nor does the novel kinase activity associated with the mcs2 cyclin oscillate (49).

Experiments in yeast have defined a number of other cell division cycle (Cdc) proteins which are also crucial for the orderly progression of the cell cycle, although the functions of many of these proteins have not been precisely defined (34). Two of these proteins, the products of the CDC20 and CDC4 genes, have been proposed to be elements of the mitotic spindle or segregational apparatus (32). The cdc20 temperature sensitive mutants arrest in mitosis at the non-permissive temperature, after the formation of a complete short spindle and nuclear migration to the neck between the mother cell and a large bud (6). It has been proposed that the Cdc20 protein is directly required for chromosomal movement (56). In addition, the Cdc20 protein is required for modulation of microtubule structure, either by promoting microtubule disassembly (1, 65) or by altering the surface of the microtubules, and is also required for microtubule-dependent processes other than mitosis (65).

The CDC4 gene of S. cerevisiae (33), is essential for the initiation of DNA synthesis. Cells carrying a conditional-lethal, temperature-sensitive mutation in cdc4 arrest division at the non-permissive temperature, and the cells have a termination phenotype of multiple buds, a single nucleus, and duplicated spindle pole bodies connected by a bridge structure (6). CDC4 also appears to be required for karyogamy and sporulation (21, 68, 71). While the mechanism of action of the Cdc4 protein is still unknown, subcellular localization studies in yeast have demonstrated that it is associated with the nucleoskeleton (7). The appearance of the duplicated spindle pole bodies has been proposed to indicate that the CDC4 gene product is required for separation of the bodies and formation of the completed spindle (6, 75). It has recently been demonstrated that removal of the centrosome (the equivalent of the spindle pole body in higher eukaryotes) from mammalian cells uncouples the growth cycle from the reproductive cycle, indicating that cell division requires the presence of centrosomes to establish the bipolar mitotic spindle (45).

It is an object of the present invention to identify one or more proteins involved in regulation of the cell cycle, wherein said proteins may be targets for compounds which modulate the cell cycle. A novel protein, termed p55CDC has been identified. mRNA encoding p55CDC was ubiquitously present in all cell lines examined, as well as in embryonic tissue, placenta and adult hematopoietic tissues, but was not detected in cells induced to differentiate and cease cell division. The deduced amino acid sequence of human p55CDC demonstrates regions of homology with the S. cerevisiae Cdc20 and Cdc4 proteins within the Gβ-repeats found in the carboxy terminal half of these three proteins. Expression of p55CDC appears to be crucial for cell division in mammalian cells. p55CDC is phosphorylated in cycling cells. Immune complexes precipitated by a polyclonal antiserum to p55CDC have a kinase activity which fluctuates during the cell cycle, although p55CDC itself does not appear to be an endogenous substrate of the kinase activity.

SUMMARY OF THE INVENTION

The invention relates to a novel mammalian protein, p55CDC, which is essential for cell division. It has been found that p55CDC is expressed in actively proliferating cells while expression is not detected in slowly dividing or quiescent cells. Transfection of antisense p55CDC cDNA into CHO cells resulted in the isolation of only those cells having a compensatory increase in p55CDC mRNA having the sense orientation.

DNA sequences encoding biologically active p55CDC are also provided by the invention. DNA sequences include rat (SEQ. ID NO: 1) and human (SEQ. ID NO: 3) p55CDC and DNA hybridizing to rat or human p55CDC, or to a fragment thereof, wherein the hybridizing DNA encodes biologically active p55CDC. Also provided for are vectors containing p55CDC DNA sequences and host cells transformed or transfected with said vectors. A method of producing a p55CDC polypeptide comprising culturing transformed or transfected host cells such that p55CDC is expressed is also included

p55CDC polypeptides of the invention will preferably form a complex with one or more host proteins such that the complex has cell-cycle dependent kinase activity. The kinase activity of p55CDC complexes will fluctuate during the cell cycle.

A method for modulating cell division is also encompassed by the invention, wherein the method comprises introducing into a cell (e.g. a tumor cell) a compound which modulates the kinase activity of p55CDC complexes. Modulation of p55CDC associated kinase activity may involve an increase or decrease in activity at certain periods during the cell cycle which in turn may lead to alterations in timing or specificity of p55CDC-associated kinase activity. In a preferred embodiment, cell division is inhibited by exposure to compounds which interfere with p55CDC complex formation.

DESCRIPTION OF THE FIGURES

FIGS. 1A-1D. Northern Analysis of p55CDC.

(A) Total RNA (30 μg) from a variety of rat tissues at different developmental stages was probed with a rat genomic 0.26 kb Pst I fragment.

B) PolyA⁺ RNA (2.5 μg) from human tissues was probed with a [³²P] labelled p55CDC cDNA from rat.

(C) PolyA⁺ RNA (2.5 μg) from human hematopoietic cell lines was analyzed with the same probe as in FIG. 1B. The signal obtained with a rat actin cDNA probe is shown for comparison.

(D) Total RNA 30 μg) prepared from cell lines that were induced to differentiate as described in Experimental Procedures and from control cells was probed with the same probe as in FIG. 1B. The ethidium bromide stain for 28SRNA is shown for comparison. All details for RNA isolation and Northern blot hybridization are described in Experimental Procedures.

FIGS. 2A-2D. Rat (SEQ ID NO:1) and Human (SEQ ID NO:3) p55CDC DNA sequence. The compiled sequence from two rat cDNA clones is shown. The open reading frame of the human cDNA is shown only where it is differs from the rat sequence. Nucleotide base pair numbers are shown to the left and amino acids, deduced from the nucleotides, are numbered at the right (SEQ ID NOs: 2 and 4). Two in frame stop codons upstream of the initiation methionine are underlined and a polyadenylation signal downstream of the stop codon is boxed.

FIGS. 3A-3C. p55CDC has seven Gβ-repeats and shows homology to the S. cerevisiae Cdc20 and Cdc4 proteins.

(A) The alignment of the seven rat p55CDC repeats (SEQ ID NOs: 5-11) was manually constructed following pairwise comparisons using the GCG BESTFIT program. Gaps were introduced to obtain optimal alignment and are represented by spaces. Identical or highly conserved residues which occur at a frequency of 4 times or greater are shown as white on black. Highly conservative substitutions are defined as Ile, Leu or Val, Ser or Thr, and Ala or Gly.

(B) and (C) Alignment of the Gβ-repeats of human p55CDC (SEQ ID NOs: 13, 16, 19, 22, 25, 28 and 30) with the Cdc20 (SEQ ID NOs: 12, 15, 18, 21, 24 and 27) and Cdc4 (SEQ ID NOs: 14, 17, 20, 23, 26, 29 and 31) repeats was obtained using the GCG BESTFIT program followed by visual optimization. Gaps were introduced to obtain optimal alignment and are represented by spaces. Identical residues are shown as white on black and The highly conserved residues are boxed. Highly conservative substitutions are defined as Ile, Leu, or Val, Ser or Thr, Ala, or Gly, Tyr or Phe, Asp or Glu and Arg. Lys or His.

FIG. 4. Southern Analysis of Genomic DNA from various species.

Genomic DNA (10 μg) from several species was digested with Hind III and separated on 1% agarose gels. The filter was probed with rat p55CDC cDNA under medium stringency conditions as defined in Materials and Methods.

FIGS. 5A-5B. Overexpression of p55CDC cDNA in the sense or antisense orientation in CHO cells results in alteration of growth profiles.

(A) CHOd⁻ cells were transfected with (Δ) PMT, (O) PMTp55s or ([]) PMTp55 as DNA and amplified as described in Materials and Methods. Cells were plated at a starting density of 0.5×10⁶ cells/60 mm dish and counted at the times shown. Arrows indicate the days when media was changed. Each point represents the mean of duplicate counts from parallel cultures which usually varied from 2-14% from the plotted mean.

(B) Flow cytometry analysis of fixed and propidium iodide stained PMTp55s (_) and PMTp55as (_) cells was performed as described in Materials and Methods.

FIGS. 6A-6B. Immune complexes detected by antibodies against p55CDC.

(A) Cell lysates from ³⁵S-labelled cells in log phase (250 μg on lanes 1, 2, 3, 6, 7, 8, 11, 12, 13, or 500 μg on lanes 4, 5, 9, 10, and 14) were immuno-precipitated with various antibodies. Immune complexes obtained with 10 μl p34^(cdc2) MAb (lanes 1, 6 and 11), p55CDC competed antiserum (8.4 μg/lane 2, 4, 7, 9, 12) and affinity purified p55CDC antiserum (1 μg/lane 3, 5, 8, 10, 13, 14) were analyzed on 10% SDS-PAGE gels. The dried gel was exposed for autoradiography for 21 hours.

(B) Cell lysates from ³⁵S-labelled cells in stationary phase (250 μg on lanes 1, 2, 3, 6, 7, 8, 11, 12, 13, or 500 μg on lanes 4, 5, 9, 10, 14, 15) were immunoprecipitated with various antibodies. Immune complexes obtained with 10 μl p34^(cdc2) MAb (lanes 1, 6, 11), p55CDC competed antiserum (8.4 μg/lane 2, 4, 7, 9, 12, 14) or affinity purified p55CDC antibody (1 μg/lane 3, 5, 8, 10, 13, 15) were analyzed on 10% SDS-PAGE gels. Autoradiography was performed for 1 week.

FIGS. 7A-7B. Histone H1 kinase activity of p55CDC immune complexes and phosphorylation of p55CDC.

(A) Lysates of CHO cell lines transfected with vector (PMT), vector with sense transcript (PMTp55s), and vector with antisense transcript (PMTp55as) were immunoprecipitated with affinity purified p55CDC antibody. Immune complexes were assayed for histone H1 kinase activity as described in Materials and Methods.

(B) CHO cells were labelled with [³²P]-orthophosphate as detailed in Materials and Methods. Immune complexes obtained from 900 μg lysate precipitated with 1 μg of affinity purified p55CDC antibody (lane 1) or 28 μg of p55CDC competed antiserum (lane 2) were analyzed by SDS-PAGE.

FIGS. 8A-8E. Immune complexes detected by p55CDC antibodies in Rat 1 and HeLa cells and their kinase activity against a variety of substrates at different stages of the cell cycle.

(A) Lysates (250 μg) from exponentially growing Rat 1 and HeLa cells were immunoprecipitated with p55CDC competed antiserum (lanes 1 and 3), affinity purified p55CDC antibody (lanes 2 and 4), and two different monoclonal antibodies against retinoblastoma protein (lanes 5 and 6).

(B) Lysates (200 μg) from HeLa cells prepared as described in Materials and Methods were immunoprecipitated with either control p55CDC competed antiserum shown in the first lane of each substrate or with affinity purified p55CDC antibody. Kinase assays were performed as described in Materials and Methods with decreasing exogenous substrate concentrations shown from left to right. The histone H1 concentrations in these assays was 0.4 mg/ml, 0.2 mg/ml and 0.1 mg/ml. Myelin basic protein (MBP) and α-casein concentrations decreased from 0.4 mg/ml to 0.1 mg/ml. The control assay was always performed using the highest substrate concentration.

(C) Lysates (200 μg) prepared from HeLa cells as described in Materials and Methods were immunoprecipitated with increasing amounts of affinity purified p55CDC antibody (0.07 μg, 0.28 μg and 1.12 μg). The negative control was done using 4.2 μg of the p55CDC competed antiserum. Kinase assays were performed as described in Materials and Methods using 0.4 mg/ml MBP as the substrate.

(D) Lysates (200 μg) were prepared from HeLa cells at various stages of the cell cycle as described in Materials and Methods and immunoprecipitated with either 8.4 μg p55CDC competed antiserum (lanes 1, 8 and 9) or 1.0 μg of affinity purified p55CDC antibody (lanes 2-7). Kinase assays were performed using 0.4 mg/ml H1, 0.4 mg/ml MBP or 0.4 mg/ml α-casein as exogenous substrates.

(E) The excised bands from the dried gel obtained in FIG. 7D were counted. The control values (FIG. 8D lanes 1, 8 and 9) were subtracted from the experimental values (FIG. 8D lanes 2-7) and the results graphed.

FIGS. 9A-9B. Cycling cells actively translate p55CDC and show high levels of associated α-casein kinase activity when compared to quiescent cells.

(A) Growing and quiescent Rat1 cells were labelled for one hour with ³⁵S-TRANSLABEL as described in Materials and Methods. Lysates (100 μg) were immunoprecipitated with various antibodies. Immune complexes obtained with 10 μl of p34^(cdc2) MAb (lanes 1 and 7, p55CDC competed antiserum (8.4 μg/lanes 2 and 8) and affinity purified P55CDC antibody (0.035 μg/lane 3, 0.14 μg/lanes 4 and 9, 0.56 μg/lanes 5 and 10, 1.12 μg/lanes 6 and 11) were analyzed by SDS-PAGE.

(B) Lysates (100 μg) were prepared from growing and quiescent Rat1 cells as described in Materials and Methods. Immune complexes were obtained with 10 μl p34^(cdc2) MAb, 8.4 μg of p55CDC competed antiserum and 1.12 μg of affinity purified p55CDC antibody. Kinase assays were performed as described in Materials and Methods using 0.4 mg/ml α-casein as substrate.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a polypeptide designated p55CDC which is involved in mammalian cell division. mRNA transcripts encoding p55CDC were expressed in embryonic tissues and adult hematopoietic tissues which comprise populations of proliferating cells, but were not detected in adult tissues lacking actively dividing cells. Moreover, human hematopoetic cell lines which were induced to differentiate with chemical agents also demonstrated loss of p55CDC transcript as cell division ceased. It has been observed that polypeptides encoded by the rat p55CDC DNA sequence (FIG. 2 and SEQ ID NO:1) and human p55CDC DNA sequence (FIG. 2 and SEQ ID NO:3) have extensive amino acid sequence homology to portions of the cdc4 and cdc20 proteins from Sacchromyces cerevisiae (FIG. 3). As cdc4 and cdc20 are both known to be involved in mitosis and cell division, this homology has suggested involvement of p55CDC in these processes as well. Additional evidence implicating p55CDC in cell division is presented in Example 2. It was shown that down-regulation of p55CDC expression by transfecting host cells with a rat p55CDC anti-sense clone resulted in surviving cells which overproduced sense transcripts, apparently to compensate for the loss of p55CDC mRNA. In addition, rat p55CDC appears to be synthesized at high levels in actively growing cells, but not in quiescent cells (Example 5).

p55CDC appears to modulate mitosis and cell division through the formation of a complex with at least one other host cell protein. Complexes containing p55CDC were precipitated by p55CDC antisera from Rat1 cells, HeLa cells, and CHO cells transfected with a rat p55CDC clone. A presumed host cell protein was observed to be associated with p55CDC in each of these cell lines (Examples 3 and 4). The p55CDC complexes from these cell lines displayed kinase activity which fluctuated during the cell cycle. The kinase activity of the p55CDC complex can be distinguished from the activities of other known cell cycle-associated kinases, including cyclin A/CDK2, cyclin E/CDK2 and cyclin B/p34cdc2 complexes, in the following ways: (1) p55CDC complexes had kinase activity against a number of substrates, including histone HI, myelin basic protein and α-casein rather than against a single substrate; and (2) a decrease in p55CDC-associated kinase activity was observed at the G₁/S transition and at the G₂/M transition. This profile of cell cycle kinase activity has not been previously observed.

The invention provides for an isolated DNA encoding a biologically active p55CDC polypeptide wherein the DNA is selected from the group consisting of:

a) DNA having a nucleotide sequence encoding the amino acid sequence of SEQ ID NO: 2;

b) DNA having a nucleotide sequence encoding the amino acid sequence of SEQ ID NO: 4; and

c) DNA having a nucleotide sequence which hybridizes with the DNA of (a) or (b), or with a fragment thereof, wherein the hybridizing DNA encodes a polypeptide having the biological activity of p55CDC.

DNA of the present invention will preferentially hybridize to DNA sequences encoding p55CDC under appropriate conditions of temperature and salt. Establishment of appropriate hybridization conditions is well within the ability of one skilled in the art using published protocols (see e.g., 63). As an example, hybridizations may be performed at 42° in 40% formamide and 5×SSPE for at least 12 hours, followed by three washes in 2×SSC, 0.1% SDS at 50° and one wash in 0.5×SSC, 0.1% SDS for 30 minutes. Sequences which hybridize with p55CDC DNA will be related by deletion, insertion, point mutation, frameshift, alternative open reading frame, or mRNA splice variant. Hybridizing sequences may also be antisense nucleic acids (DNA or RNA) which bind to p55CDC DNA or RNA so as to modulate the expression of p55CDC. Antisense nucleic acids may target the p55CDC coding region or regulatory sequences involved in transcription and/or translation of p55CDC.

DNA sequences hybridizing to p55CDC DNA will preferably encode for a polypeptide having the biological activity of p55CDC. As shown in Examples 3 and 4, p55CDC associates with one or more host proteins to form a complex wherein said complex has cell cycle-dependent kinase activity. The biological activity of p55CDC, as described herein, refers to a complex-associated kinase activity which is active on various substrates such as histone H1, α-casein and myelin basic protein, and wherein the kinase activity on one or more substrates is modulated during the cell cycle. For example, the kinase activity of p55CDC complexes on α-casein is diminished during the G₁/S and G₂/M transitions of the mammalian cell cycle.

The invention also relates to a p55CDC polypeptide as the product of procaryotic or eucaryotic expression of an exogenous DNA sequence, that is, p55CDC is preferably recombinant p55CDC. Exogenous DNA encoding p55CDC may be genomic DNA, cDNA, or may be partially or completely synthetic DNA. In one embodiment, p55CDC DNA includes one or more codons which are preferred for expression in procaryotic host cells, especially E. coli host cells. Synthesis of DNA fragments for assembly into sequences for p55CDC expression is accomplished using synthetic methods which are readily available to one skilled in the art, such as those described in Engels et al. (Angew. Chem. Intl. Ed. 28, 716-734 (1989)).

Also provided by the invention are plasmids and host cells for the expression of p55CDC protein. p55CDC expression may be accomplished in procaryotic or eucaryotic hosts (e.g., mammalian, plant or insect cells, yeast or bacterial cells). Preferred host cells include mammalian cells, such as Chinese Hamster ovary (CHO) cells, or bacterial hosts such as Escherichia coli. p55CDC may be expressed from a variety of plasmid or viral vectors which are appropriate for the host cell being used. The use of vector pMT for the expression of rat p55CDC in CHO cells is described in Example 2. However, other vectors that are suitable for p55CDC expression in other host cells may also be used. Expression of p55CDC in transgenic animals may be obtained using expression vectors and DNA transfection procedures available to one skilled in the art.

A method for producing a p55CDC polypeptide is also included. The method comprises culturing a procaryotic or eucaryotic host cell into which an expression vector containing a p55CDC DNA sequence has been transformed or transfected such that a p55CDC polypeptide is expressed.

An isolated p55CDC polypeptide is encompassed by the present invention. Such polypeptides may be produced by expression of DNA molecules encoding p55CDC, or they may be produced by chemical synthesis of peptides using procedures available to one skilled in the art. p55CDC polypeptides produced by the aforementioned biological or chemical methods are isolated using purification techniques which are known to one skilled in the art. p55CDC polypeptides may be analogs of rat or human polypeptides shown in SEQ ID NO: 2 or SEQ ID NO: 4, respectively, wherein said analogs comprise the substitution, deletion or insertion of one or more amino acids. In addition, chemical synthesis of p55CDC polypeptides allows the inclusion of non-naturally occurring amino acids (e.g., D-amino acids) at selected positions. Amino acid residues within the p55CDC polypeptide which are required for activity are determined by generating analogs and testing said analogs for activity, such as the ability to form a complex having cell cycle associated kinase activity, or the ability to advance a host cell through the cell cycle. Protein kinase assays described in Materials and Methods can be used to test for the biological activity of p55CDC analogs. Selected regions of a p55CDC polypeptide, such as those which show homology to the cell division proteins cdc4 and cdc20 (see FIG. 3), may be used to design biologically active p55CDC analogs or peptide fragments. These regions are referred to as Gβ repeats and are likely to be important in the structure and/or function of p55CDC.

Antibodies specifically binding p55CDC polypeptides of the invention are also provided. Antibodies may be polyclonal or monoclonal and may recognize fragments, analogs and fusion polypeptides of p55CDC as well as the intact protein. Mouse anti-p55CDC antibodies may be produced by techniques available to one skilled in the art and may be modified to form chimeric or humanized antibodies. Anti-p55CDC antibodies are useful in assays described below for quantitating p55CDC and p55CDC complexes that are present in biological samples.

A complex comprising p55CDC and at least one other host cell protein is also provided. Example 3 describes an immune complex from tranfected CHO cells having p55CDC and an associated 210 kDa protein wherein the complex has cell cycle associated kinase activity. Example 4 describes immune complexes from rat 1 and Hela cells which have p55CDC associated with a second polypeptide and exhibit kinase activity. A 110 kDa protein was identified in rat immune complexes and a 100 kDa protein was identified in Hela immune complexes. The ability of p55CDC to associate with at least one other polypeptide such that the resulting complex phosphorylates various host cell molecules appears to correlate with the ability of p55CDC to modulate the cell cycle. Also encompassed by the invention are complexes comprising a p55CDC analog and at least one other host cell protein. In a preferred embodiment, p55CDC complexes will have cell cycle dependent kinase activity such as that described in Example 4.

The invention also relates to a method for detecting levels of p55CDC in biological samples. The method comprises incubating an antibody specifically binding p55CDC, or a fragment, analog, or fusion polypeptide thereof, with a sample under conditions suitable for forming a complex between the antibody and p55CDC and detecting the presence of a p55CDC-antibody complex. The antibody may also bind to p55CDC when p55CDC is complexed with other host cell proteins. Therefore, the method also encompasses the detection of p55CDC complexes. Since p55CDC is present in actively dividing cells, but not in quiescent cells, it is anticipated that a diagnostic assay for p55CDC will be most useful in identifying those samples having elevated levels of cell division.

Methods for modulating cell division are also provided. It will be appreciated by one skilled in the art that compounds which modulate p55CDC activity will modulate cell cycle activity as well. Compounds which modulate the synthesis of p55CDC and/or modulate the ability of p55CDC to form a complex having cell cycle associated kinase activity may be identified using the procedures described for determining p55CDC activity. Modulation of p55CDC kinase activity may involve an increase or decrease in activity at certain periods during the cell cycle which may lead to alterations in the timing or specificity of p55CDC complex activity, Compounds which in turn may be used to control cell division include, but are not limited to, the following: (1) compounds which increase or decrease the levels of p55CDC synthesis; (2) compounds which bind to p55CDC so as to interfere with formation of a p55CDC complex having kinase activity; (3) compounds which compete with p55CDC for complex formation and themselves form inactive complexes; and (4) compounds which promote the formation of the p55CDC complex or stabilize said complex from dissociation by increasing the half-life. Examples include nucleic acid molecules which bind to p55CDC DNA or p55CDC polypeptides, antibodies, peptides, organic molecules, and carbohydrates. Such compounds are identified by screening large repetoires, or libraries, comprising nucleic acids, peptides or small organic molecules derived from chemical synthesis or natural sources (e.g., bacteria, fungi, plants). Considerable literature exists on the synthesis, characterization and screening of very large natural or synthetic libraries of molecules or polymers. One skilled in the art would appreciate that such libraries can be screened for compounds that modulate p55CDC activity.

Compounds which inhibit the biosynthesis or activity of p55CDC are useful in inhibiting the growth of those tumor cells having increased levels of p55CDC or increased levels of cell cycle dependent kinase activity associated with p55CDC as compared to normal, noncancerous cells. Compounds useful as chemotherapeutic agents include, but are not limited to, the following: (1) compounds which decrease the levels of p55CDC synthesis; (2) compounds which bind to p55CDC so as to interfere with formation of a p55CDC-host cell protein complex having kinase activity; and (3) compounds which compete with p55CDC for association with one or more host cell proteins involved in complex formation and themselves form inactive complexes. Tumor cells which grow more rapidly than normal, noncancerous cells perhaps by virtue of increased p55CDC activity may be more responsive to p55CDC-inhibiting agents. Such agents would be expected to have less effect on p55CDC activity in normal cells.

A method of chemotherapy comprising treating a mammal with an amount of a compound which is effective in reducing or inhibiting p55CDC activity in a pharmaceutically effective adjuvant is also provided. Compounds which reduce or inhibit p55CDC activity are identified by screening appropriate sources for activity against p55CDC using assays for p55CDC activity as described herein. A dosage which is effective in reducing or inhibiting p55CDC activity may be determined by one skilled in the art taking into account such factors as the condition being treated and administration regimen. Important considerations include the type and location of the tumor being treated and whether the route of administration is by injection (intravenous, intramuscular, or subcutaneous) or by oral or nasal intake. Compounds of the present invention are mixed with a pharmaceutically acceptable adjuvant which may include any suitable buffer, solubilizer, preservative, carrier or anti-oxidant. Preferably, the adjuvant will not decrease the p55CDC-inhibiting activity of the compound. An extensive survey of pharmaceutically acceptable ajuvants is found in Remington's Pharmaceutical Sciences, 18th ed. A. R. Gennaro, ed. Mack, Easton, Pa. (1990).

EXAMPLE 1 Identification and Characterization of p55CDC

The p55CDC Gene

The gene encoding p55CDC was identified serendipitously during an attempt to identify novel glycosyltransferase enzymes by low stringency screening of a rat genomic library with cDNA encoding the rat α2, 6 sialyltransferase (57, 73). During one round of screening, a genomic clone was isolated. Restriction map analysis first narrowed the hybridizing region to a 2 kb Bgl II fragment. The cross hybridizing region of this fragment was further narrowed to a 0.26 kb Pst I fragment which was used for Northern analysis of various embryonic, neonatal and adult rat tissues. This identified a tissue which could be used as a source of RNA for construction of a cDNA library.

Northern analysis revealed tissue-specific and developmentally-regulated expression of a unique transcript (FIG. 1A). A 2 kb mRNA was abundant in RNA from total rat embryo, and this transcript was enriched in embryonic rat liver. However, in two day old neonatal rats, the level of message in the liver decreased precipitously. The transcript was still abundant in spleen from 2 day old rats, and a small amount was present in kidney. In 16 day old rats, the transcript was still abundant in spleen and thymus, but was barely detectable in liver and kidney. The transcript was not detectable in any adult tissues, although a longer exposure of a blot containing more RNA did reveal a faint band in the spleen sample. The presence of the transcript in hematopoietic tissues, such as neonatal liver, thymus and spleen, suggested that expression of this novel gene was highest in tissues in which cell proliferation was occuring.

A cDNA library was constructed using polyA+ RNA from two day old rat spleen. Using the Pst I genomic fragment as a probe, several positive plaques were identified, at a frequency of approximately 1:15,000. The two largest cDNA inserts were subcloned and sequenced. The nucleotide sequence (FIG. 2 and SEQ ID NO: 1) coded for a protein of 499 amino acids, with a predicted molecular mass of 55 kDa. However, this sequence did not appear to encode a classical glycosyltransferase enzyme, since there was no evidence of an amino-terminal hydrophobic membrane spanning signal-anchor domain, which is essential for glycosyltransferases to be properly oriented in the Golgi (57).

The human p55CDC gene was isolated from an HT1080 cell line cDNA library by the following procedures. The nucleotide sequence and deduced amino acid sequence are shown in FIG. 2 and in SEQ ID NO: 3. A comparison of the open reading frames of the rat and human sequences showed an 87% identity at the nucleotide level, which increased to 95% at the amino acid level. Differences in the human nucleotide sequence are shown above the rat sequence, and differences in the human amino acid sequence are shown below. The human sequence diverged considerably from the rat upstream of the ATG start site, and also in the 3′ untranslated region.

Homology of p55CDC to Cell Cycle Proteins

A search of the genEMBL database revealed that rat and human p55CDC proteins had seven regions of homology with the WD-40 repeat of the β subunit of G proteins (27) (FIG. 3A), and to a number of proteins which contain this imperfect repeat motif (for review, see 12, 72). These included the products of the S. cerevisiae genes CDC20 (65) and CDC4 (77), TUP1/AER2 (78), PRP4 (58), and MSI1 (62), as well as the products of the D. melanogaster gene Espl, the D. discoidum gene AAC3 (66), the Arabidopsis thaliana gene COP1 (13) and the dTAF₁₁80 subunit of Drosophila TF11D (22). The highest degree of homology, illustrated in FIG. 3B, was seen between p55CDC and the two S. cerevisiae cell division cycle proteins, Cdc20 (519 amino acids) and Cdc4 (779 amino acids). The BESTFIT analysis revealed a 45% identity between amino acids 172-407 of p55CDC and amino acids 249-479 of the Cdc20 protein, which increased to 59% when highly conserved substitutions were included. This was the only protein in which a high degree of similarity was found with the degenerate internal Gβ-repeats in p55CDC. The Cdc4 protein was the only protein which showed strong homology with all seven repeats found in p55CDC, using the first seven of the nine repeats found in the Cdc4 protein (FIG. 3B). The alignment of the highly degenerate WD-40 repeats in these two proteins required the introduction of 16 gaps over 300 amino acid residues. This comparison indicated that 28% of the residues in this region were identical, and 41% were identical or highly conserved. Notably, the S. cerevisiae Cdc20 and Cdc4 proteins each displayed a greater degree of homology to the mammalian p55CDC protein than they did to each other.

Recently a clone isolated from a Xenopus oocyte cDNA library by virtue of its ability to suppress the temperature sensitive defect of the S. Cerevisiae cdc15 mutation, was shown to encode a protein of 518 amino acids that has seven Gβ-repeats in its carboxy terminal half (69). This protein called βTrCP (β-transducin repeat containing protein) was not a functional homolog of CDC20, though overexpression of both these genes is capable of suppressing the cdc15 mutation (1, 69). Both βTrCP and p55CDC have seven Gβ-repeats and show 24% identity over this region.

The only protein that showed significant homology to p55CDC extending beyond the Gβ-repeats was the S. cerevisiae MSI1 protein, which is a negative regulator of the RAS-mediated induction of cAMP levels (62). The MSI1 protein (422 amino acids) was 24% identical to p55CDC, and this increased to 28% when only the amino terminal 178 residues of p55CDC were compared to the amino terminal 148 residues of MSI1.

Cross Species Homology of p55CDC

A high degree of evolutionary conservation within the p55CDC open reading frame was seen when genomic DNA from a variety of mammalian species, chicken, D. melanogaster and S. cerevisiae were examined by Southern blot analysis, using the rat cDNA probe (FIG. 4). A cross-hybridizing species was detectable in all the mammalian and the avian species, although no bands were seen in the lanes containing S. cerevisiae and D. melanogaster DNA. These results also indicate that the gene encoding p55CDC is a single copy gene, with no closely related genes in the species examined.

Expression of p55CDC in Tissues and Cell Lines

The pattern of expression of p55CDC mRNA in embryonic and neonatal rat tissues, and the apparent relationship between p55CDC and the S. cerevisiae Cdc20 and Cdc4 proteins suggesting a possible role for p55CDC in cell division, prompted us to examine other developing mammalian tissues for p55CDC expression. Northern analysis of human tissues demonstrated a pattern of expression similar to that seen in the rat, with high levels of expression in fetal liver and juvenile thymus, but no expression seen in fetal lung, adult lung or liver, or adult buffy coat, which is primarily comprised of non-dividing white blood cells (FIG. 1B). A second Northern analysis examining polyA⁺ RNA from adult human heart, brain, placenta, lung, liver, skeletal muscle, kidney and pancreas demonstrated expression of p55CDC in only one tissue, the placenta, which contains actively dividing cells; a similar pattern of expression has been described for p34^(cdc2) (48).

A number of human cell lines also expressed the p55CDC transcript. The transcript was abundant in all leukemia cell lines examined, including the T cell lines MOLT 4f and CEM, the B cell lines Raji and Ramos, the monocytic cell line U937 and the myeloerythroid cell line K562 (FIG. 1C). Indeed, we observed expression of the p55CDC transcript in every cell line examined at log phase of growth, regardless of lineage.

To examine whether expression of the p55CDC transcript was related to the ability of cells to divide, we took advantage of the unique properties of two leukemia cell lines, K-562 and HL-60. K-562 cells can be induced by treatment with sodium butyrate to undergo erythroid differentiation with no significant effect on growth rate (2). In contrast, treatment of K-562 cells with the phorbol ester TPA causes monocytic differentiation accompanied by growth arrest (5). Treatment of HL-60 cells with TPA also causes monocytic differentiation, with arrest of DNA synthesis and cell division (61). We examined the effects of these agents on the level of expression of p55CDC mRNA in these two cell lines (FIG. 1D). The p55 transcript was easily detectable in both mock-treated cell lines. For both K-562 and HL-60, treatment of the cells with TPA resulted in loss of p55CDC mRNA expression. In the K-562 cells treated with sodium butyrate, in which differentiation is not accompanied by growth arrest, the level of p55CDC transcript was roughly equal to that found in the mock-treated cells. These results indicate that p55CDC mRNA is synthesized only in dividing cells.

EXAMPLE 2 Effects of p55CDC on Cell Proliferation

To explore possible functions of the p55CDC protein, CHOd− cells were transfected with plasmid containing the cDNA encoding the rat p55CDC in either the sense (PMTp55s) or antisense (PMTp55as) orientation. A 1.8 kb fragment of rat cDNA was inserted downstream of the metallothionein promoter in the pMT010/A+ mammalian expression vector (9). This vector also contains two dominant selectable markers, the bacterial neo gene and the mouse DHFR gene, driven by the SV40 promoter. Control cells were transfected with vector alone (PMT). Following amplification with methotrexate, the three pools of cells were plated at a density of 0.5×10⁶ cells per 60 mm plate in the presence of 0.05 mM zinc, and the growth profiles plotted for fourteen days (FIG. 5A). Pools of transfected cells were studied, rather than individual clones, to minimize the effect of any clonal variation in the CHOd⁻ cells. Initially, little difference in the growth rates were observed among the three pools of transfected cells, although the PMTp55as cells were significantly larger than the PMTp55s or control cells as shown by forward scatter analysis determined by flow cytometry and visual observation under the microscope. Moreover, a DNA content analysis as measured by propidium iodide uptake showed that PMTp55as cells had an increased amount of DNA/cell, indicating that these cells were hyperdiploid (FIG. 5B). As the plates began to reach confluence, dramatic differences in the growth profiles were observed. The PMTp55 as cells reached confluence first, at a lower cell number, consistent with their layer size. After reaching confluence the PMTp55as cells continued to divide slowly. The smaller PMTp55s cells continued to divide at a faster rate after reaching confluence. The PMTp55s cells reached a density of 24×10⁶ cells/plate by day 14, compared to 6×10⁶ cells/plate for the PMTp55as cells. The growth profile of the PMT cells fell midway between those of the PMTp55s and PMTp55as cells.

Since the cells transfected with the vector encoding an antisense transcript continued to survive, although with an altered phenotype, we examined the pools of transfected cells for the presence of sense and antisense p55CDC mRNA transcripts using an RNAse protection assay (70). As shown in Table 1, the PMT cells had an average of 166 copies of sense mRNA per cell, while, as expected, the PMTp55s cells had an increased average of 734 copies of sense mRNA per cell. Surprisingly, the PMTp55as cells also had an increased number of copies of sense mRNA, with an average of 714 copies per cell. In addition, the PMTp55as cells had only a moderate amount of antisense mRNA, with an average of 205 copies per cell, despite having been transfected with cDNA encoding the antisense transcript. This same pattern was observed when clonal cell lines isolated from the pools of cells were analyzed. Each of the four PMTp55as clonal lines made elevated amounts of the sense transcript; in all lines, this amount was at least five times the amount of the antisense transcript. As expected, in the control PMT cells, the average number of copies of sense transcript per cell declined considerably in confluent cells.

TABLE 1 p55CDC mRNA copy number in both sense and antisense orientation in various cell lines 48 hours 7 days mRNA copies/cell^(a) mRNA copies/cell^(a) Cell Line Sense Anti-Sense Sense Anti-sense PMT 166 ± 6  —  4 ± 7 — PMTp55s 734 ± 40  21 ± 7 240 ± 9  16 ± 5  PMTp55as 714 ± 10  205 ± 10 263 ± 10 96 ± 10 PMTp55A2s 771 ± 12 2  ND^(b) ND PMTp5SB6s 4136 ± 66  117 ± 4 ND ND PMTp55B12as 706 ± 20 126 ± 3 ND ND PMTp55G6as 1176 ± 10   213 ± 14 ND ND PMTp55H5as 928 ± 17 157 ± 2 ND ND PMTp55H11as 1149 ± 21  128 ± 7 ND ND ^(a)Values were determined as described in experimental procedures. ^(b)Not Determined

Genomic DNA analysis of all six clonal cell lines demonstrated that the elevated expression of sense transcripts was not due to amplification of the endogenous gene. The two clonal isolates expressing sense orientation transcripts were distinct from one another. In contrast, it is likely that all four of the PMTp55as clones we isolated derived from the expansion of only one transfected cell in the original pool of cells, since restriction map analyses of the four clonal PMTp55as cell lines using two different restriction enzymes and two different probes, to detect either plasmid or p55CDC sequences, demonstrated identical banding patterns. The results indicated that inhibition of p55CDC expression by antisense transcripts was compensated for by overexpression of sense transcripts. This data suggested that p55CDC was essential for maintenance of cell proliferation in culture.

EXAMPLE 3 Immune Complexes Containing p55CDC

Polyclonal rabbit antiserum was raised against a fusion protein consisting of p55CDC and glutathione S-transferase. Both the original antiserum and an affinity purified antibody preparation precipitated a protein of M_(r) 55 kDa from an in vitro transcription/translation reaction containing p55CDC cDNA, consistent with the predicted mass of the polypeptide.

To examine the level of p55CDC production in the transfected cell lines, immunoprecipitations were performed on extracts of ³⁵S-labelled cells in log phase, using the affinity purified antibody. As shown in FIG. 6A, the PMTp55s and PMTp55as cells had increased levels of p55CDC compared to the PMT cells, consistent with the demonstration of increased numbers of transcripts encoding p55CDC in these cells. In the PMTp55s cells, there was a strong band of 31 kDa which probably represents a degradation product of p55CDC, since this band was also detected on immunoblot analyses of cell extracts using the polyclonal antibody preparation. This 31 kDa band was also observed when cell lysates were prepared without protease inhibitors, and no intact p55CDC was detected in the absence of protease inhibitors. This peptide was not p34^(cdc2), since no p34^(cdc2) protein was detected in any of the immune complexes.

Immunoprecipitates of p55CDC also contained a protein of M_(r) 210 kDa. The amount of p210 detected in the immunoprecipitates was roughly proportional to the amount of p55CDC. When this experiment was repeated on cells in stationary phase, seven days after plating, a significant decrease in the amounts of both p55CDC and p210 is observed (FIG. 6B); in FIG. 6B, a one week exposure of the autoradiogram was required to detect p55CDC, compared to a 21 hour exposure in FIG. 6A. These results indicate that production of p55CDC is highest in proliferating cells.

EXAMPLE 4 Kinae Activity of p55CDC Immune Complexes

Since many events in the cell cycle are controlled by various kinases, it was of interest to determine whether p55CDC immune complexes had any kinase activity. All immune complexes examined for protein kinase activity were precipitated under conditions identical to those used in FIG. 6. The immunoprecipiptation buffer was formulated (1% NP-40, 1% deoxycholate and 0.1% SDS) to minimize non-specific protein association. A number of cell division kinases can phosphorylate histone H1, so this substrate was assayed first. As shown in FIG. 7A, immune complexes precipitated with p55CDC antibody phosphorylated histone H1. Immune complexes prepared from lysates of the PMT, PMTp55s and PMTp55as cells all demonstrated kinase activity against histone H1. The highest levels of phosphorylation were seen in the PMTp55s and PMTp55as cells which have increased expression of p55CDC. In the negative controls, using competed antiserum, a small amount of residual activity is seen. In reactions performed without addition of exogenous substrates, no phosphorylated proteins were detected, indicating that none of the proteins in the immune complex are endogenous substrates of the kinase activity. However, when all three pools of transfected cells were labelled with [³²P]-orthophosphate and p55CDC was immunoprecipitated, SDS-PAGE analysis revealed that p55CDC was phosphorylated (FIG. 7B). Thus, p55CDC is a substrate of another endogenous kinase in the CHO cells. In the PMTp55s cells, no ³²P-labelled 31 kDa band was detected (see FIG. 6A and B, lanes 8 and 10), indicating that the 31 kDa degradation fragment of p55CDC is either not phosphorylated, or is dephosphorylated prior to degradation.

We wished to examine whether p55CDC in different cell lines was associated with other proteins in immune complexes and whether these complexes also had kinase activity. The Rat1 fibroblast and HeLa cell lines were chosen for this analysis. Proliferating Rat1 and HeLa cells were lysed, and immune complexes precipitated with the affinity purified p55CDC antibody (FIG. 8A, lanes 2 and 4). SDS-PAGE analysis of the immune complexes did not reveal the 210 kDa band seen in CHO cells, but did reveal other discrete bands which appeared to be cell-specific. In the Rat1 cells, a protein of 110 kDa was present in the p55CDC immune complexes, while a protein of 100 kDa was seen in p55CDC immune complexes in HeLa cells.

The p55CDC immune complexes from HeLa cells were examined for kinase activity against a number of different substrates (FIG. 8B). Kinase activity was detected with histone H1, myelin basic protein and a-casein, with maximal activity detected with myelin basic protein. β-casein was also examined, but minimal activity was detected with β-casein as a substrate (data not shown). The level of kinase activity correlated with p55CDC concentration, since increasing the amount of antibody used for the immunoprecipitation resulted in increased phosphorylation of myelin basic protein (FIG. 8C).

To determine whether the p55CDC-associated kinase activity fluctuated during the cell cycle, as has been described for the cyclin-dependent kinases, cells were arrested at various points in the cell cycle and immune complexes precipitated from cell lysates were examined for kinase activity. A distinct pattern of a cell cycle related fluctuation in kinase activity was detected with only one of the three substrates examined, α-casein (FIGS. 8D and E). Kinase activity against α-casein was present in HeLa cells and in cells blocked in G₁ by serum starvation. The level of activity against α-casein dropped approximately four-fold in cells arrested at G₁/S and returned to the higher levels in cells harvested during S phase. Kinase activity remained constant in cells in the G₂ stage of the cell cycle and decreased six-fold in cells at the G_(2/)M transition. Kinase activity against histone H1 by p55CDC immune complexes was stable throughout the cell cycle (FIG. 8E). Backgound levels of histone H1 kinase activity in the G_(2/)M cells (FIG. 8D, lane 8) was most likely due to residual p34^(cdc2) kinase activity in these samples. Kinase activity against myelin basic protein was also relatively constant throughout the cell cycle, with the exception of the G₂/M transition, where a two-fold decrease in activity was observed. While p55CDC was difficult to detect by immunoblotting of cell lysates prepared from cells at any of the various stages, the amount of p55CDC present in cells did not appear to fluctuate during the cell cycle, in contrast to the fluctuation in kinase activity observed with p55CDC immune complexes.

EXAMPLE 5 p55CDC Expression and Kinase Activity in Growing and Quiescent Cells

The expression of p55CDC and the associated kinase activity in growing and quiescent populations of cells was compared by exploiting the ability of Rat1 cells to arrest growth under limiting serum conditions. As shown in FIG. 9A, exponentially growing Rat1 cells actively synthesized labelled p55CDC (lanes 3-6), while the quiescent population showed minimal production of p55CDC within the one hour labelling period (lanes 9-11). To rule out that the kinase activity we observed was precipated non-specifically from the cell lysates, increasing amounts of p55CDC antibody were used in the immunoprecipitations. As shown in lanes 3-6, increasing the amount of p55CDC antibody resulted in the precipitation of increasing levels of p55CDC. This result is consistent with the result observed in FIG. 8C, where increasing the amount of antibody used for precipitation increased the level of p55CDC kinase activity detected. The production of labelled p34^(cdc2) is also substantially reduced in the quiescent population (compare lanes 1 and 7), although the amount of total p34^(cdc2) in the two samples was virtually equivalent, as detected on Coomassie blue stained gels of immunoprecipitated material. We also examined the p55CDC associated kinase activity under these two conditions and compared it to that observed for p34^(cdc2) immune complexes as a control. A higher level of activity was observed with the p55CDC complexes using α-casein as a substrate, since α-casein is a poor substrate for the p34^(cdc2) kinase (FIG. 9B). Both the p34^(cdc2) kinase and the p55CDC associated kinase showed a decrease in activity in the quiescent cells. As seen in the HeLa cells, when myelin basic protein was used as a substrate, no significant change in the p55CDC associated kinase activity was observed.

Materials and Methods

RNA Analysis

Total RNA was prepared from freshly dissected rat tissues, human thymus and buffy coat, by the method of Chomczynski and Sacchi (8). mRNA from human cell lines was prepared by the FASTTRACK kit (Invitrogen). Gel electrophoresis of total RNA (30 μg/lane) was done in 1% agarose gels containing formaldehyde and Northern hybridizations were performed as reported earlier (73). Radiolabelled probes were genereated using the Amersham Multiprime DNA labelling system RPN.1601. mRNA size was determined by comparing with commercial RNA standards (Bethesda Research Laboratories, Gaithersburg, Md.). mRNA from other human tissues was purchased from Clontech as was a multiple human tissue Northern blot.

To generate the riboprobes for the RNAse protection assay, the gel purified p55CDC cDNA fragment was subcloned in pBLUESCRIPT (Stratagene, LaJolla, Calif.) in both the sense and antisense orientation relative to the T7 promoter. All subsequent steps were performed as described previously (70). Briefly, cells (1×10⁶/ml) were washed in phosphate buffered saline (PBS) and lysed by incubation at room temperature for 20 minutes in 10 mM Tris pH 8.0, 1 mM EDTA, 20 mM dithiothreitol, 100 μg/ml proteinase K and 0.2% SDS. Lysed samples were added to hybridization mix with the labeled riboprove and incubated at 84° for 2 hours. Following RNAse digestion for 20 minutes at 37° using RNAse A and RNAse T1, the sample was loaded onto a SEPHACRYL S200 Superfine gel filtration column (Sigma, St. Louis, Mo.) and the void volume fraction containing the protected rpobe was counted. The quantity of gene specific RNA was calculated from a standard curve. All assays were performed n duplicate.

DNA Analysis

Genomic Southerns and restriction map analysis were performed using standard molecular biology techniques (63), Genomic DNA from various species was purchased from Clontech (Palo Alto, Calif.). Medium stringency hybridizations were performed at 42° in 40% formamide. All hybridizations were performed at a salt concentration of 5×SSPE. Following overnight hybridizations the filters were washed three times in 2×SSC, 0.1% SDS at 50°. The final wash was done in 0.5×SSX, 0.1% SDS for 30 minutes. DNA sequence was determined using SEQUENASE (U.S. Biochemical), following the manufacturer's protocol. Sequencing was also performed on the Applied Biosystems 373A automated DNA sequencer using the Tag Dye Deoxy Terminator kit according to suggested protocol. The comparative percent identity values between the genes carrying the Gβ motif were obtained using the GCG BESTFIT program with gap weight set at 2.0 and length weight at 0.05.

cDNA Cloning of Rat P55CDC

A rat genomic library made from a partial EcoRI digest ligated into Charon 4A (Clontech) was screened at low stringency (hybridizations performed in 43% formamide at 37°) with a 435 base pair cDNA probe encompassing amino acid residues 141-286 of the a2, 6 sialytransferase gene (73). Restriction map analysis of the isolated genomic clone revealed a 2 kb Bgl II fragment that hybridized to the probe. This fragment was subcloned into a pUC vector and further analysis narrowed the hybridizing region to a 0.26 It Pst I fragment which was used in all subsequent analysis. PolyA⁺ RNA from newborn rat spleen was selected by two cycles of binding to oligo (dT)-cellulose type 2 (Collaborative Research). A cDNA library was constructed using the Pharmacia cDNA synthesis kit followed by ligation into the λgt10 vector. This was packaged using the GIGAPACK II Gold cloning kit (Stratagene). An initial packaging reaction gave 3.3×10⁶ pfu and 1×10⁶ pfu were screened using the 0.26 kb Pst I fragment as probe.

cDNA Cloning of Human p55CDC

The human HT1080 cell line cDNA library was constructed in the pSPORT-1 plasmid vector (BRL Life Technologies, Inc.). DNA from 44 pools of approximately 5000 colonies each was linearized with Not I and screened by Southern blot, using the rat pS5CDC cDNA as a probe. Plaque and colony purification of the clones with the longest inserts was done using standard techniques (63).

Cell Culture, Synchronization and Labelling

HL60 and K562 cells were grown in RPMI1640 (Irvine Scientific, Irvine, Calif.) supplemented with 10 mM HEPES and 15% fetal calf serum. Cells were seeded at a concentration of 0.2×10⁶ cells/ml media. Cells treated with 1mM sodium butyrate were grown in 75 cm² flasks for three days. Cells induced with phorbol ester were grown in the presence of 30 ng/ml 12-O-teradecanoyl-phorbol 13-acetate (TPA) for three days. Cells were lysed by guanidine thiocyanate and total RNA prepared as described (8). CHOd− cells were maintained in Dulbecco's modified Eagle's medium (DMEM) supplemented with 5% fetal calf serum, glutamine, non-essential amino acids and hypoxanthine. Rat 1 cells were maintained in DMEM containing 10% serum and glutamine and HeLa cells in a Minimum Essential Medium supplemented with 10% serum, glutamine and non-essential amino acids.

HeLa cells were synchronized at the beginning of S phase (G₁/S) by the double thymidine/aphidicolin block described by Heintz et al (35). Cells harvested 4 hours later were in S phase (59). Synchronization at the G₂/M transition was achieved by growth in the presence of 0.5 μg/ml nocodazole for a period of 12-14 hours. The media was carefully suctioned off and the non-adherent mitotic cells were harvested by gently pipetting buffer onto the monolayer. The adherent cells were washed with PBS and then lysed. This population is not mitotic and is predominantly in G₂ (36).

Asynchronous exponentially growing cells were grown in methionine and cysteine free media containing 2% dialyzed serum for one hour followed by two hours in the same media containing 100 μCi/ml media of ³⁵S Translabel (ICN Biomedicals, Irvine, Calif.). [³²P]-orthophosphate (ICN Biomedicals) labelling was performed for 3 hours following a one hour preincubation in phosphate deficient media.

Rat1 cells were growth arrested by rinsing the plates with PBS, followed by rinsing in media containing 0.1% fetal calf serum. The cells were grown in the low serum media for 48 hours to obtain a quiescent population. Labelling with ³⁵S-Translabel was performed as described above, with the exception that the dialyzed serum concentration was maintained at 0.1% and the label was incorporated over one hour. For the exponentially growing population of Rat1 cells, the dialyzed serum concentration was maintained at 2% during the course of the labelling.

For flow cytometry analysis, 1×10⁶ cells were washed in PBS and fixed in 70% ethanol, 2.0% Triton X-100 for one hour. Fixed cells were washed in PBS and stained in a solution of 50 μg/ml propidium iodide (PI) and 20 μg/ml RNAse A. The cells were analysed for DNA content (fluorescent intensity) and cell size (forward scatter) using the FACScan (Becton Dickinson, Mountain View, Calif.).

Transfection of CHOd− Cells.

A 1.8 kb cDNA obtained from the newborn rat spleen library was cloned into the Bam H1 site of the pMT010/A+ mammalian expression vector (9). The cDNA was inserted downstream of the metallothionein promoter in both the sense (PMTp55s) and antisense (PMTp55as) orientations. These plasmids, as well as vector alone as control, were transfected into cells using Lipofectin (BRL Life Technologies) following the suggested protocol. Initial selection by Geneticin at 400 μg/ml in media without hypoxanthine was followed by stepwise amplification by methotrexate to a final concentration of 2 μM. Growth curves were performed in media containing 0.05 mM zinc to induce the metallothionein promoter.

Antibody Preparation

A p55CDC cDNA clone lacking the first 10 codons was inserted into the EcoR1 site of the pGEX-3X vector (Pharmacia GST gene fusion system). Competent XL-1 cells (Stratagene) were transformed and a colony harboring the recombinant plasmid was isolated. Cultures were induced with isopropyl β-D-thiogalactopyranoside (final concentration 0.1 mM) for growth of the fusion protein. A 76 kDa insoluble fusion protein was obtained which stayed with the pellet following sonication and solubilization with 1% Triton CF-54. The pellet obtained from lysed and sonicated cells was washed twice with PBS containing 1% Triton CF-54 and the resulting pellet extracted with 10M urea. All attempts to extract the fusion protein in anything short of 10M urea failed. The urea extract was dialyzed overnight against PBS and the resulting suspension stored in aliquots at ˜80° C. until further purification by SDS-PAGE electrophoresis. The pellets were resuspended in SDS sample buffer and separated in 10% SDS gels. The region between the visible standard markers of 55 kDa and 80 kDa was excised out and the protein recovered by electroelution (Biorad Model 422 ElectroEluter). This preparation was mixed with Freund's complete adjuvant and used for immunization of rabbits. A booster injection was given after four weeks using Freund's incomplete adjuvant. Animals were bled 10-14 days following a booster injection. To obtain an affinity column for purification of antiserum, the crude insoluble fusion protein pellet was resuspended in coupling buffer (0.1M NaHCO3 pH 8.3, 0.5M NaCl, 0.5% SDS) and coupled to cyanogen bromide-activated Sepharose, according to the manufacturer's instructions (Pharmacia, Piscataway, N.J.). A coupling efficiency of approximately 0.4 mg protein/ml gel was achieved. The antiserum was first absorbed against an unrelated insoluble fusion protein to remove any antibodies reactive against glutathione S-transferase or contaminating E. coli proteins. This partially purified antiserum was applied to the affinity column. The column was washed with 5× column volumes of PBS and the affinity purified antibodies were eluted with 3M sodium thiocyanate. Pooled antibody fractions were immediately dialyzed against PBS and stored at −80° C. The flowthrough fraction from this column was used as competed antiserum.

Immunoprecipitations and Protein Kinase Assays

In vitro translation was performed using a nuclease treated rabbit reticulocyte lysate (Promega. Madison Wis.) and [³H]-leucine (Amersham TRK 683). The mRNA template was produced by using the Stratagene in Vitro transcription kit and the p55CDC cDNA subcloned into the pBLUESCRIPT vector as substrate. Cell lysates were prepared as described (59) after rinsing the plates twice with PBS. Cells were lysed in modified radioimmunoprecipitation assay (RIPA) buffer with additional proteases (150 mM NaCl, 1.0% NP-40, 1.0% sodium deoxycholate, 0.1% SDS 2 mM EDTA, 6 mM Na₂HPO₄, 4 mM NaH₂PO₄ 50 mM NaF, 200 μM Na₃VO₄, 20 μg/ml aprotinin, 1 μg/ml leupeptin 10 μg/ml soybean trypsin inhibitor and 50 μg/ml phenylmethyl sulfonyl fluoride). All protease inhibitors were purchased from Sigma. Protein concentrations were estimated using the Bicinchoninic acid reagent (Pierce). For 250 μg lysate in a final volume of 700 μl RIPA buffer, we used 7 μl of affinity purified p55CDC antibodies (140 μg protein/ml) or 12 μl of p55CDC competed antiserum (700 μg protein/ml) which gave an equivalent level of immunoglobulin for both preparations. Immunoprecipitation of the p34^(cdc2) complexes was done using 10 μl of the p34^(cdc2) mouse monoclonal antibody 17 (Santa Cruz Biotechnology, Santa Cruz, Calif.). Other antibodies used in this study were Rb (1F8), a mouse monoclonal IgG against a Rb-β galactoside fusion protein (Santa Cruz Biotechnology) and Rb (Ab-1), another monoclonal antibody against retinoblastoma protein (Oncogene Science, Uniondale, N.Y.). The immune complexes were routinely incubated overnight on ice and collected next morning with 30 μl of a 50% slurry of Protein G-SEPHAROSE (Pharmacia). The washed pellets were assayed for histone H1 kinase activity as described in (59). All reactions were performed for 30 minutes at 30°. Assays were also performed using a variety of kinase substrates at the indicated concentrations, using the same assay conditions. Histone H1 was purchased from Boehringer Mannheim while myelin basic protein (MBP), β-casein and α-casein were all purchased from Sigma. The reaction products were quantitated by excising the stained bands from the dried gel and counting.

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While the present invention has been described in terms of the preferred embodiments, it is understood that variations and modifications will occur to those skilled in the art. Therefore, it is intended that the appended claims cover all such equivalent variations which come within the scope of the invention as claimed.

                   #             SEQUENCE LISTING <160> NUMBER OF SEQ ID NOS: 31 <210> SEQ ID NO 1 <211> LENGTH: 1767 <212> TYPE: DNA <213> ORGANISM: Rattus sp. <220> FEATURE: <221> NAME/KEY: CDS <222> LOCATION: (193)..(1689) <400> SEQUENCE: 1 ggcgtgcctt tagccggtca gaaaagaacg cattcggcac ttctacagac gc #actgagga     60 gtcagggatt tgtgtttggg agaggtttac gaagaggtgc tgggctggtg cg #aactgtgg    120 caggcagagc ccaggagtcc tgcgaggtcc tgagtttggt cgcctctcac cc #ccctcccc    180 ggtagacggg cc atg gcg cag ttc gtg ttc gag agc # gat ttg cat tca ctg    231               Met Ala Gl #n Phe Val Phe Glu Ser Asp Leu His Ser Leu                 1   #             5      #             10 ctt caa ctg gac gcg ccc atc ccc aat gca cc #g att gct cgc tgg cag      279 Leu Gln Leu Asp Ala Pro Ile Pro Asn Ala Pr #o Ile Ala Arg Trp Gln      15              #     20              #     25 cgc aaa gca aaa gaa gcc aca ggc cca gcc cc #c tcg cct atg cgg gcc      327 Arg Lys Ala Lys Glu Ala Thr Gly Pro Ala Pr #o Ser Pro Met Arg Ala  30                  # 35                  # 40                  # 45 gcc aac aga tca cac agc gcc ggt cgg acc cc #g ggc cga act cct ggc      375 Ala Asn Arg Ser His Ser Ala Gly Arg Thr Pr #o Gly Arg Thr Pro Gly                  50  #                 55  #                 60 aaa tct aat tct aag gtt cag acc acc cct ag #c aaa cct gga ggt gag      423 Lys Ser Asn Ser Lys Val Gln Thr Thr Pro Se #r Lys Pro Gly Gly Glu              65      #             70      #             75 cgc tat atc ccc caa cgt agt gct tcc caa at #g gag gtg gcc agc ttc      471 Arg Tyr Ile Pro Gln Arg Ser Ala Ser Gln Me #t Glu Val Ala Ser Phe          80          #         85          #         90 ctc ttg agc aag gag aac cag ccg gaa gac gg #g ggt acg ccc acc aag      519 Leu Leu Ser Lys Glu Asn Gln Pro Glu Asp Gl #y Gly Thr Pro Thr Lys      95              #    100              #    105 aag gag cat cag aaa gcc tgg gct cgg aac ct #g aac ggt ttt gat gtg      567 Lys Glu His Gln Lys Ala Trp Ala Arg Asn Le #u Asn Gly Phe Asp Val 110                 1 #15                 1 #20                 1 #25 gag gaa gcc aag atc ctc agg ctc agt gga aa #a cct cag aat gcc cca      615 Glu Glu Ala Lys Ile Leu Arg Leu Ser Gly Ly #s Pro Gln Asn Ala Pro                 130   #               135   #               140 gaa ggc tac cag aac aga ttg aaa gta ctc ta #c agc cag aaa gcc acg      663 Glu Gly Tyr Gln Asn Arg Leu Lys Val Leu Ty #r Ser Gln Lys Ala Thr             145       #           150       #           155 cct ggc tcc agt cgg aag gct tgc aga tac at #t cct tcc ctg cca gac      711 Pro Gly Ser Ser Arg Lys Ala Cys Arg Tyr Il #e Pro Ser Leu Pro Asp         160           #       165           #       170 agg att ctt gat gcc cct gaa atc cgg aat ga #c tac tac ctg aat ctt      759 Arg Ile Leu Asp Ala Pro Glu Ile Arg Asn As #p Tyr Tyr Leu Asn Leu     175               #   180               #   185 gtc gat tgg agc tct gga aat gta tta gct gt #g gca ctg gac aac agt      807 Val Asp Trp Ser Ser Gly Asn Val Leu Ala Va #l Ala Leu Asp Asn Ser 190                 1 #95                 2 #00                 2 #05 gtg tac tta tgg aac gct ggt tcc ggt gac at #c ctg cag ctg ttg caa      855 Val Tyr Leu Trp Asn Ala Gly Ser Gly Asp Il #e Leu Gln Leu Leu Gln                 210   #               215   #               220 atg gag cag cct ggg gac tac ata tca tcc gt #g gcc tgg atc aaa gag      903 Met Glu Gln Pro Gly Asp Tyr Ile Ser Ser Va #l Ala Trp Ile Lys Glu             225       #           230       #           235 ggc aac tac ctg gct gtg ggc acc agt aat gc #t gag gtg cag cta tgg      951 Gly Asn Tyr Leu Ala Val Gly Thr Ser Asn Al #a Glu Val Gln Leu Trp         240           #       245           #       250 gat gtg cag cag cag aaa cgg ctt cga aac at #g acc agc cac tct gct      999 Asp Val Gln Gln Gln Lys Arg Leu Arg Asn Me #t Thr Ser His Ser Ala     255               #   260               #   265 cga gta agc tcc ctg agt tgg aac agc tat at #c ctg tca agt ggt tca     1047 Arg Val Ser Ser Leu Ser Trp Asn Ser Tyr Il #e Leu Ser Ser Gly Ser 270                 2 #75                 2 #80                 2 #85 cga tct ggc cac atc cac cac cac gat gtt cg #a gta gca gaa cac cat     1095 Arg Ser Gly His Ile His His His Asp Val Ar #g Val Ala Glu His His                 290   #               295   #               300 gtg gcc aca ctg agt ggc cat agc cag gaa gt #a tgt ggg ctg cgc tgg     1143 Val Ala Thr Leu Ser Gly His Ser Gln Glu Va #l Cys Gly Leu Arg Trp             305       #           310       #           315 gcc cca gat gga cga cat ctg gca agc ggt gg #c aat gat aac att gtc     1191 Ala Pro Asp Gly Arg His Leu Ala Ser Gly Gl #y Asn Asp Asn Ile Val         320           #       325           #       330 aac gtg tgg cct agt ggt cct gga gaa agt gg #c tgg gtt ccc ctg cag     1239 Asn Val Trp Pro Ser Gly Pro Gly Glu Ser Gl #y Trp Val Pro Leu Gln     335               #   340               #   345 aca ttc act caa cat caa ggt gct gtc aag gc #t gtt gca tgg tgt ccc     1287 Thr Phe Thr Gln His Gln Gly Ala Val Lys Al #a Val Ala Trp Cys Pro 350                 3 #55                 3 #60                 3 #65 tgg cag tcc aat atc ctg gca aca gga gga gg #t acc agt gac cga cac     1335 Trp Gln Ser Asn Ile Leu Ala Thr Gly Gly Gl #y Thr Ser Asp Arg His                 370   #               375   #               380 att cgc att tgg aac gtc tgc tct gga gcc tg #t ctg agt gct gtg gat     1383 Ile Arg Ile Trp Asn Val Cys Ser Gly Ala Cy #s Leu Ser Ala Val Asp             385       #           390       #           395 gtg cat tcc cag gtg tgc tcc atc ctc tgg tc #t ccc cac tat aag gag     1431 Val His Ser Gln Val Cys Ser Ile Leu Trp Se #r Pro His Tyr Lys Glu         400           #       405           #       410 ctc atc tca ggc cat ggc ttt gcc cag aac ca #g ctg gtt att tgg aag     1479 Leu Ile Ser Gly His Gly Phe Ala Gln Asn Gl #n Leu Val Ile Trp Lys     415               #   420               #   425 tac cca acc atg gcc aag gtg gca gag ctc aa #a ggt cac aca gcc cgg     1527 Tyr Pro Thr Met Ala Lys Val Ala Glu Leu Ly #s Gly His Thr Ala Arg 430                 4 #35                 4 #40                 4 #45 gtc ctg agt ctc acc atg agt cca gac ggg gc #c aca gtg gca tct gca     1575 Val Leu Ser Leu Thr Met Ser Pro Asp Gly Al #a Thr Val Ala Ser Ala                 450   #               455   #               460 gca gcc gat gag act ctg cgg ctc tgg cgc tg #c ttt gag ctg gac cct     1623 Ala Ala Asp Glu Thr Leu Arg Leu Trp Arg Cy #s Phe Glu Leu Asp Pro             465       #           470       #           475 gcc ctt cgg cgg gag cgg gaa aaa gcc agc ac #a tct aaa agt agc ctc     1671 Ala Leu Arg Arg Glu Arg Glu Lys Ala Ser Th #r Ser Lys Ser Ser Leu         480           #       485           #       490 atc cac caa ggc atc cgg tgaaagacaa ccctttcttt tc #ccttcttg            1719 Ile His Gln Gly Ile Arg     495 attttgttgt tgtttatttt tttctaataa agttcatatc ttcctttc   #              1767 <210> SEQ ID NO 2 <211> LENGTH: 499 <212> TYPE: PRT <213> ORGANISM: Rattus sp. <400> SEQUENCE: 2 Met Ala Gln Phe Val Phe Glu Ser Asp Leu Hi #s Ser Leu Leu Gln Leu   1               5  #                 10  #                 15 Asp Ala Pro Ile Pro Asn Ala Pro Ile Ala Ar #g Trp Gln Arg Lys Ala              20      #             25      #             30 Lys Glu Ala Thr Gly Pro Ala Pro Ser Pro Me #t Arg Ala Ala Asn Arg          35          #         40          #         45 Ser His Ser Ala Gly Arg Thr Pro Gly Arg Th #r Pro Gly Lys Ser Asn      50              #     55              #     60 Ser Lys Val Gln Thr Thr Pro Ser Lys Pro Gl #y Gly Glu Arg Tyr Ile  65                  # 70                  # 75                  # 80 Pro Gln Arg Ser Ala Ser Gln Met Glu Val Al #a Ser Phe Leu Leu Ser                  85  #                 90  #                 95 Lys Glu Asn Gln Pro Glu Asp Gly Gly Thr Pr #o Thr Lys Lys Glu His             100       #           105       #           110 Gln Lys Ala Trp Ala Arg Asn Leu Asn Gly Ph #e Asp Val Glu Glu Ala         115           #       120           #       125 Lys Ile Leu Arg Leu Ser Gly Lys Pro Gln As #n Ala Pro Glu Gly Tyr     130               #   135               #   140 Gln Asn Arg Leu Lys Val Leu Tyr Ser Gln Ly #s Ala Thr Pro Gly Ser 145                 1 #50                 1 #55                 1 #60 Ser Arg Lys Ala Cys Arg Tyr Ile Pro Ser Le #u Pro Asp Arg Ile Leu                 165   #               170   #               175 Asp Ala Pro Glu Ile Arg Asn Asp Tyr Tyr Le #u Asn Leu Val Asp Trp             180       #           185       #           190 Ser Ser Gly Asn Val Leu Ala Val Ala Leu As #p Asn Ser Val Tyr Leu         195           #       200           #       205 Trp Asn Ala Gly Ser Gly Asp Ile Leu Gln Le #u Leu Gln Met Glu Gln     210               #   215               #   220 Pro Gly Asp Tyr Ile Ser Ser Val Ala Trp Il #e Lys Glu Gly Asn Tyr 225                 2 #30                 2 #35                 2 #40 Leu Ala Val Gly Thr Ser Asn Ala Glu Val Gl #n Leu Trp Asp Val Gln                 245   #               250   #               255 Gln Gln Lys Arg Leu Arg Asn Met Thr Ser Hi #s Ser Ala Arg Val Ser             260       #           265       #           270 Ser Leu Ser Trp Asn Ser Tyr Ile Leu Ser Se #r Gly Ser Arg Ser Gly         275           #       280           #       285 His Ile His His His Asp Val Arg Val Ala Gl #u His His Val Ala Thr     290               #   295               #   300 Leu Ser Gly His Ser Gln Glu Val Cys Gly Le #u Arg Trp Ala Pro Asp 305                 3 #10                 3 #15                 3 #20 Gly Arg His Leu Ala Ser Gly Gly Asn Asp As #n Ile Val Asn Val Trp                 325   #               330   #               335 Pro Ser Gly Pro Gly Glu Ser Gly Trp Val Pr #o Leu Gln Thr Phe Thr             340       #           345       #           350 Gln His Gln Gly Ala Val Lys Ala Val Ala Tr #p Cys Pro Trp Gln Ser         355           #       360           #       365 Asn Ile Leu Ala Thr Gly Gly Gly Thr Ser As #p Arg His Ile Arg Ile     370               #   375               #   380 Trp Asn Val Cys Ser Gly Ala Cys Leu Ser Al #a Val Asp Val His Ser 385                 3 #90                 3 #95                 4 #00 Gln Val Cys Ser Ile Leu Trp Ser Pro His Ty #r Lys Glu Leu Ile Ser                 405   #               410   #               415 Gly His Gly Phe Ala Gln Asn Gln Leu Val Il #e Trp Lys Tyr Pro Thr             420       #           425       #           430 Met Ala Lys Val Ala Glu Leu Lys Gly His Th #r Ala Arg Val Leu Ser         435           #       440           #       445 Leu Thr Met Ser Pro Asp Gly Ala Thr Val Al #a Ser Ala Ala Ala Asp     450               #   455               #   460 Glu Thr Leu Arg Leu Trp Arg Cys Phe Glu Le #u Asp Pro Ala Leu Arg 465                 4 #70                 4 #75                 4 #80 Arg Glu Arg Glu Lys Ala Ser Thr Ser Lys Se #r Ser Leu Ile His Gln                 485   #               490   #               495 Gly Ile Arg <210> SEQ ID NO 3 <211> LENGTH: 1700 <212> TYPE: DNA <213> ORGANISM: Homo sapiens <220> FEATURE: <221> NAME/KEY: CDS <222> LOCATION: (117)..(1613) <400> SEQUENCE: 3 gtcgacccac gcgtccgggc gtaagccagg cgtgttaaag ccggtcggaa ct #gctccgga     60 gggcacgggc tccgtaggca ccaactgcaa ggacccctcc ccctgcgggc gc #tccc atg    119                    #                   #                   #        Met                    #                   #                   #          1 gca cag ttc gcg ttc gag agt gac ctg cac tc #g ctg ctt cag ctg gat      167 Ala Gln Phe Ala Phe Glu Ser Asp Leu His Se #r Leu Leu Gln Leu Asp               5     #              10     #              15 gca ccc atc ccc aat gca ccc cct gcg cgc tg #g cag cgc aaa gcc aag      215 Ala Pro Ile Pro Asn Ala Pro Pro Ala Arg Tr #p Gln Arg Lys Ala Lys          20          #         25          #         30 gaa gcc gca ggc ccg gcc ccc tca ccc atg cg #g gcc gcc aac cga tcc      263 Glu Ala Ala Gly Pro Ala Pro Ser Pro Met Ar #g Ala Ala Asn Arg Ser      35              #     40              #     45 cac agc gcc ggc agg act ccg ggc cga act cc #t ggc aaa tcc agt tcc      311 His Ser Ala Gly Arg Thr Pro Gly Arg Thr Pr #o Gly Lys Ser Ser Ser  50                  # 55                  # 60                  # 65 aag gtt cag acc act cct agc aaa cct ggc gg #t gac cgc tat atc ccc      359 Lys Val Gln Thr Thr Pro Ser Lys Pro Gly Gl #y Asp Arg Tyr Ile Pro                  70  #                 75  #                 80 cat cgc agt gct gcc cag atg gag gtg gcc ag #c ttc ctc ctg agc aag      407 His Arg Ser Ala Ala Gln Met Glu Val Ala Se #r Phe Leu Leu Ser Lys              85      #             90      #             95 gag aac cag tct gaa aac agc cag acg ccc ac #c aag aag gaa cat cag      455 Glu Asn Gln Ser Glu Asn Ser Gln Thr Pro Th #r Lys Lys Glu His Gln         100           #       105           #       110 aaa gcc tgg gct ttg aac ctg aac ggt ttt ga #t gta gag gaa gcc aag      503 Lys Ala Trp Ala Leu Asn Leu Asn Gly Phe As #p Val Glu Glu Ala Lys     115               #   120               #   125 atc ctt cgg ctc agt gga aaa cca caa aat gc #g cca gag ggt tat cag      551 Ile Leu Arg Leu Ser Gly Lys Pro Gln Asn Al #a Pro Glu Gly Tyr Gln 130                 1 #35                 1 #40                 1 #45 aac aga ctg aaa gta ctc tac agc caa aag gc #c act cct ggc tcc agc      599 Asn Arg Leu Lys Val Leu Tyr Ser Gln Lys Al #a Thr Pro Gly Ser Ser                 150   #               155   #               160 cgg aag acc tgc cgt tac att cct tcc ctg cc #a gac cgt atc ctg gat      647 Arg Lys Thr Cys Arg Tyr Ile Pro Ser Leu Pr #o Asp Arg Ile Leu Asp             165       #           170       #           175 gcg cct gaa atc cga aat gac tat tac ctg aa #c ctt gtg gat tgg agt      695 Ala Pro Glu Ile Arg Asn Asp Tyr Tyr Leu As #n Leu Val Asp Trp Ser         180           #       185           #       190 tct ggg aat gta ctg gcc gtg gca ctg gac aa #c agt gtg tac ctg tgg      743 Ser Gly Asn Val Leu Ala Val Ala Leu Asp As #n Ser Val Tyr Leu Trp     195               #   200               #   205 agt gca agc tct ggt gac atc ctg cag ctt tt #g caa atg gag cag cct      791 Ser Ala Ser Ser Gly Asp Ile Leu Gln Leu Le #u Gln Met Glu Gln Pro 210                 2 #15                 2 #20                 2 #25 ggg gaa tat ata tcc tct gtg gcc tgg atc aa #a gag ggc aac tac ttg      839 Gly Glu Tyr Ile Ser Ser Val Ala Trp Ile Ly #s Glu Gly Asn Tyr Leu                 230   #               235   #               240 gct gtg ggc acc agc agt gct gag gtg cag ct #a tgg gat gtg cag cag      887 Ala Val Gly Thr Ser Ser Ala Glu Val Gln Le #u Trp Asp Val Gln Gln             245       #           250       #           255 cag aaa cgg ctt cga aat atg acc agt cac tc #t gcc cga gtg ggc tcc      935 Gln Lys Arg Leu Arg Asn Met Thr Ser His Se #r Ala Arg Val Gly Ser         260           #       265           #       270 cta agc tgg aac agc tat atc ctg tcc agt gg #t tca cgt tct ggc cac      983 Leu Ser Trp Asn Ser Tyr Ile Leu Ser Ser Gl #y Ser Arg Ser Gly His     275               #   280               #   285 atc cac cac cat gat gtt cgg gta gca gaa ca #c cat gtg gcc aca ctg     1031 Ile His His His Asp Val Arg Val Ala Glu Hi #s His Val Ala Thr Leu 290                 2 #95                 3 #00                 3 #05 agt ggc cac agc cag gaa gtg tgt ggg ctg cg #c tgg gcc cca gat gga     1079 Ser Gly His Ser Gln Glu Val Cys Gly Leu Ar #g Trp Ala Pro Asp Gly                 310   #               315   #               320 cga cat ttg gcc agt ggt ggt aat gat aac tt #g gtc aat gtg tgg cct     1127 Arg His Leu Ala Ser Gly Gly Asn Asp Asn Le #u Val Asn Val Trp Pro             325       #           330       #           335 agt gct cct gga gag ggt ggc tgg gtt cct ct #g cag aca ttc acc cag     1175 Ser Ala Pro Gly Glu Gly Gly Trp Val Pro Le #u Gln Thr Phe Thr Gln         340           #       345           #       350 cat caa ggg gct gtc aag gcc gta gca tgg tg #t ccc tgg cag tcc aat     1223 His Gln Gly Ala Val Lys Ala Val Ala Trp Cy #s Pro Trp Gln Ser Asn     355               #   360               #   365 gtc ctg gca aca gga ggg ggc acc agt gat cg #a cac att cgc atc tgg     1271 Val Leu Ala Thr Gly Gly Gly Thr Ser Asp Ar #g His Ile Arg Ile Trp 370                 3 #75                 3 #80                 3 #85 aat gtg tgc tct ggg gcc tgt ctg agt gcc gt #g gat gcc cat tcc cag     1319 Asn Val Cys Ser Gly Ala Cys Leu Ser Ala Va #l Asp Ala His Ser Gln                 390   #               395   #               400 gtg tgc tcc atc ctc tgg tct ccc cat tac aa #g gag ctc atc tca ggc     1367 Val Cys Ser Ile Leu Trp Ser Pro His Tyr Ly #s Glu Leu Ile Ser Gly             405       #           410       #           415 cat ggc ttt gca cag aac cag cta gtt att tg #g aag tac cca acc atg     1415 His Gly Phe Ala Gln Asn Gln Leu Val Ile Tr #p Lys Tyr Pro Thr Met         420           #       425           #       430 gcc aag gtg gct gaa ctc aaa ggt cac aca tc #c cgg gtc ctg agt ctg     1463 Ala Lys Val Ala Glu Leu Lys Gly His Thr Se #r Arg Val Leu Ser Leu     435               #   440               #   445 acc atg agc cca gat ggg gcc aca gtg gca tc #c gca gca gca gat gag     1511 Thr Met Ser Pro Asp Gly Ala Thr Val Ala Se #r Ala Ala Ala Asp Glu 450                 4 #55                 4 #60                 4 #65 acc ctg agg cta tgg cgc tgt ttt gag ttg ga #c cct gcg cgg cgg cgg     1559 Thr Leu Arg Leu Trp Arg Cys Phe Glu Leu As #p Pro Ala Arg Arg Arg                 470   #               475   #               480 gag cgg gag aag gcc agt gca gcc aaa agc ag #c ctc atc cac caa ggc     1607 Glu Arg Glu Lys Ala Ser Ala Ala Lys Ser Se #r Leu Ile His Gln Gly             485       #           490       #           495 atc cgc tgaagaccaa cccatcacct cagttgtttt ttatttttct aa #taaagtca      1663 Ile Arg tgtctccctt catgtttttt tttttaaaaa aaaaaaa       #                   #    1700 <210> SEQ ID NO 4 <211> LENGTH: 499 <212> TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE: 4 Met Ala Gln Phe Ala Phe Glu Ser Asp Leu Hi #s Ser Leu Leu Gln Leu   1               5  #                 10  #                 15 Asp Ala Pro Ile Pro Asn Ala Pro Pro Ala Ar #g Trp Gln Arg Lys Ala              20      #             25      #             30 Lys Glu Ala Ala Gly Pro Ala Pro Ser Pro Me #t Arg Ala Ala Asn Arg          35          #         40          #         45 Ser His Ser Ala Gly Arg Thr Pro Gly Arg Th #r Pro Gly Lys Ser Ser      50              #     55              #     60 Ser Lys Val Gln Thr Thr Pro Ser Lys Pro Gl #y Gly Asp Arg Tyr Ile  65                  # 70                  # 75                  # 80 Pro His Arg Ser Ala Ala Gln Met Glu Val Al #a Ser Phe Leu Leu Ser                  85  #                 90  #                 95 Lys Glu Asn Gln Ser Glu Asn Ser Gln Thr Pr #o Thr Lys Lys Glu His             100       #           105       #           110 Gln Lys Ala Trp Ala Leu Asn Leu Asn Gly Ph #e Asp Val Glu Glu Ala         115           #       120           #       125 Lys Ile Leu Arg Leu Ser Gly Lys Pro Gln As #n Ala Pro Glu Gly Tyr     130               #   135               #   140 Gln Asn Arg Leu Lys Val Leu Tyr Ser Gln Ly #s Ala Thr Pro Gly Ser 145                 1 #50                 1 #55                 1 #60 Ser Arg Lys Thr Cys Arg Tyr Ile Pro Ser Le #u Pro Asp Arg Ile Leu                 165   #               170   #               175 Asp Ala Pro Glu Ile Arg Asn Asp Tyr Tyr Le #u Asn Leu Val Asp Trp             180       #           185       #           190 Ser Ser Gly Asn Val Leu Ala Val Ala Leu As #p Asn Ser Val Tyr Leu         195           #       200           #       205 Trp Ser Ala Ser Ser Gly Asp Ile Leu Gln Le #u Leu Gln Met Glu Gln     210               #   215               #   220 Pro Gly Glu Tyr Ile Ser Ser Val Ala Trp Il #e Lys Glu Gly Asn Tyr 225                 2 #30                 2 #35                 2 #40 Leu Ala Val Gly Thr Ser Ser Ala Glu Val Gl #n Leu Trp Asp Val Gln                 245   #               250   #               255 Gln Gln Lys Arg Leu Arg Asn Met Thr Ser Hi #s Ser Ala Arg Val Gly             260       #           265       #           270 Ser Leu Ser Trp Asn Ser Tyr Ile Leu Ser Se #r Gly Ser Arg Ser Gly         275           #       280           #       285 His Ile His His His Asp Val Arg Val Ala Gl #u His His Val Ala Thr     290               #   295               #   300 Leu Ser Gly His Ser Gln Glu Val Cys Gly Le #u Arg Trp Ala Pro Asp 305                 3 #10                 3 #15                 3 #20 Gly Arg His Leu Ala Ser Gly Gly Asn Asp As #n Leu Val Asn Val Trp                 325   #               330   #               335 Pro Ser Ala Pro Gly Glu Gly Gly Trp Val Pr #o Leu Gln Thr Phe Thr             340       #           345       #           350 Gln His Gln Gly Ala Val Lys Ala Val Ala Tr #p Cys Pro Trp Gln Ser         355           #       360           #       365 Asn Val Leu Ala Thr Gly Gly Gly Thr Ser As #p Arg His Ile Arg Ile     370               #   375               #   380 Trp Asn Val Cys Ser Gly Ala Cys Leu Ser Al #a Val Asp Ala His Ser 385                 3 #90                 3 #95                 4 #00 Gln Val Cys Ser Ile Leu Trp Ser Pro His Ty #r Lys Glu Leu Ile Ser                 405   #               410   #               415 Gly His Gly Phe Ala Gln Asn Gln Leu Val Il #e Trp Lys Tyr Pro Thr             420       #           425       #           430 Met Ala Lys Val Ala Glu Leu Lys Gly His Th #r Ser Arg Val Leu Ser         435           #       440           #       445 Leu Thr Met Ser Pro Asp Gly Ala Thr Val Al #a Ser Ala Ala Ala Asp     450               #   455               #   460 Glu Thr Leu Arg Leu Trp Arg Cys Phe Glu Le #u Asp Pro Ala Arg Arg 465                 4 #70                 4 #75                 4 #80 Arg Glu Arg Glu Lys Ala Ser Ala Ala Lys Se #r Ser Leu Ile His Gln                 485   #               490   #               495 Gly Ile Arg <210> SEQ ID NO 5 <211> LENGTH: 43 <212> TYPE: PRT <213> ORGANISM: Rattus sp. <400> SEQUENCE: 5 Ile Pro Ser Leu Pro Asp Arg Ile Leu Asp Al #a Pro Glu Ile Arg Asn   1               5  #                 10  #                 15 Asp Tyr Tyr Leu Asn Leu Val Asp Trp Ser Se #r Gly Asn Val Leu Ala              20      #             25      #             30 Val Ala Leu Asp Asn Ser Val Tyr Leu Trp As #n          35          #         40 <210> SEQ ID NO 6 <211> LENGTH: 44 <212> TYPE: PRT <213> ORGANISM: Rattus sp. <400> SEQUENCE: 6 Ala Gly Ser Gly Asp Ile Leu Gln Leu Leu Gl #n Met Glu Gln Pro Gly   1               5  #                 10  #                 15 Asp Tyr Ile Ser Ser Val Ala Trp Ile Lys Gl #u Gly Asn Tyr Leu Ala              20      #             25      #             30 Val Gly Thr Ser Asn Ala Glu Val Gln Leu Tr #p Asp          35          #         40 <210> SEQ ID NO 7 <211> LENGTH: 40 <212> TYPE: PRT <213> ORGANISM: Rattus sp. <400> SEQUENCE: 7 Val Gln Gln Gln Lys Arg Leu Arg Asn Met Th #r Ser His Ser Ala Arg   1               5  #                 10  #                 15 Val Ser Ser Leu Ser Trp Asn Ser Tyr Ile Le #u Ser Ser Gly Ser Arg              20      #             25      #             30 Ser Gly His Ile His His His Asp          35          #         40 <210> SEQ ID NO 8 <211> LENGTH: 43 <212> TYPE: PRT <213> ORGANISM: Rattus sp. <400> SEQUENCE: 8 Val Arg Val Ala Glu His His Val Ala Thr Le #u Ser Gly His Ser Gln   1               5  #                 10  #                 15 Glu Val Cys Gly Leu Arg Trp Ala Pro Asp Gl #y Arg His Leu Ala Ser              20      #             25      #             30 Gly Gly Asn Asp Asn Ile Val Asn Val Trp Pr #o          35          #         40 <210> SEQ ID NO 9 <211> LENGTH: 49 <212> TYPE: PRT <213> ORGANISM: Rattus sp. <400> SEQUENCE: 9 Ser Gly Pro Gly Glu Ser Gly Trp Val Pro Le #u Gln Thr Phe Thr Gln   1               5  #                 10  #                 15 His Gln Gly Ala Val Lys Ala Val Ala Trp Cy #s Pro Trp Gln Ser Asn              20      #             25      #             30 Ile Leu Ala Thr Gly Gly Gly Thr Ser Asp Ar #g His Ile Arg Ile Trp          35          #         40          #         45 Asn <210> SEQ ID NO 10 <211> LENGTH: 43 <212> TYPE: PRT <213> ORGANISM: Rattus sp. <400> SEQUENCE: 10 Val Cys Ser Gly Ala Cys Leu Ser Ala Val As #p Val His Ser Gln Val   1               5  #                 10  #                 15 Cys Ser Ile Leu Trp Ser Pro His Tyr Lys Gl #u Leu Ile Ser Gly His              20      #             25      #             30 Gly Phe Ala Gln Asn Gln Leu Val Ile Trp Ly #s          35          #         40 <210> SEQ ID NO 11 <211> LENGTH: 42 <212> TYPE: PRT <213> ORGANISM: Rattus sp. <400> SEQUENCE: 11 Tyr Pro Thr Met Ala Lys Val Ala Glu Leu Ly #s Gly His Thr Ala Arg   1               5  #                 10  #                 15 Val Leu Ser Leu Thr Met Ser Pro Asp Gly Al #a Thr Val Ala Ser Ala              20      #             25      #             30 Ala Ala Asp Glu Thr Leu Arg Leu Trp Arg          35          #         40 <210> SEQ ID NO 12 <211> LENGTH: 39 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 12 Pro Glu Arg Ile Leu Asp Ala Pro Gly Phe Gl #n Asp Asp Phe Tyr Leu   1               5  #                 10  #                 15 Asn Leu Leu Ser Trp Ser Lys Lys Asn Val Le #u Ala Ile Ala Leu Asp              20      #             25      #             30 Thr Ala Leu Tyr Leu Trp Asn          35 <210> SEQ ID NO 13 <211> LENGTH: 40 <212> TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE: 13 Leu Pro Asp Arg Ile Leu Asp Ala Pro Glu Il #e Arg Asn Asp Tyr Tyr   1               5  #                 10  #                 15 Leu Asn Leu Val Asp Trp Ser Ser Gly Asn Va #l Leu Ala Val Ala Leu              20      #             25      #             30 Asp Asn Ser Val Tyr Leu Trp Ser          35          #         40 <210> SEQ ID NO 14 <211> LENGTH: 52 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 14 Leu Ser Asp Glu Ile Phe Ser Ala Ile Asn As #n Asn Leu Pro His Ala   1               5  #                 10  #                 15 Tyr Phe Lys Asn Leu Leu Phe Arg Leu Val Al #a Asn Met Asp Arg Ser              20      #             25      #             30 Glu Leu Ser Asp Leu Gly Thr Leu Ile Lys As #p Asn Leu Lys Arg Asp          35          #         40          #         45 Leu Ile Thr Ser      50 <210> SEQ ID NO 15 <211> LENGTH: 42 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 15 Ala Thr Thr Gly Asp Val Ser Leu Leu Thr As #p Phe Glu Asn Thr Thr   1               5  #                 10  #                 15 Ile Cys Ser Val Thr Trp Ser Asp Asp Asp Cy #s His Ile Ser Met Ala              20      #             25      #             30 Lys Glu Asp Gly Asn Thr Glu Ile Trp Asp          35          #         40 <210> SEQ ID NO 16 <211> LENGTH: 44 <212> TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE: 16 Ala Ser Ser Gly Asp Ile Leu Gln Leu Leu Gl #n Met Glu Gln Pro Gly   1               5  #                 10  #                 15 Glu Tyr Ile Ser Ser Val Ala Trp Ile Lys Gl #u Gly Asn Tyr Leu Ala              20      #             25      #             30 Val Gly Thr Ser Ser Ala Glu Val Gln Leu Tr #p Asp          35          #         40 <210> SEQ ID NO 17 <211> LENGTH: 67 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 17 Leu Pro Phe Glu Ile Ser Leu Lys Ile Phe As #n Tyr Leu Gln Phe Glu   1               5  #                 10  #                 15 Asp Ile Ile Asn Ser Leu Gly Val Ser Gln As #n Trp Asn Lys Ile Ile              20      #             25      #             30 Arg Lys Ser Thr Ser Leu Trp Lys Lys Leu Le #u Ile Ser Glu Asn Phe          35          #         40          #         45 Val Ser Pro Lys Gly Phe Asn Ser Leu Asn Le #u Lys Leu Ser Gln Lys      50              #     55              #     60 Tyr Pro Lys  65 <210> SEQ ID NO 18 <211> LENGTH: 41 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 18 Val Glu Thr Met Ser Leu Ile Arg Thr Met Ar #g Ser Gly Leu Gly Val   1               5  #                 10  #                 15 Arg Ile Gly Ser Leu Ser Trp Leu Asp Thr Le #u Ile Ala Thr Gly Ser              20      #             25      #             30 Arg Ser Gly Glu Ile Gln Ile Asn Asp          35          #         40 <210> SEQ ID NO 19 <211> LENGTH: 40 <212> TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE: 19 Val Gln Gln Gln Lys Arg Leu Arg Asn Met Th #r Ser His Ser Ala Arg   1               5  #                 10  #                 15 Val Gly Ser Leu Ser Trp Asn Ser Tyr Ile Le #u Ser Ser Gly Ser Arg              20      #             25      #             30 Ser Gly His Ile His His His Asp          35          #         40 <210> SEQ ID NO 20 <211> LENGTH: 64 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 20 Leu Ser Gln Gln Asp Arg Leu Arg Leu Ser Ph #e Leu Glu Asn Ile Phe   1               5  #                 10  #                 15 Ile Leu Lys Asn Trp Tyr Asn Pro Lys Phe Va #l Pro Gln Arg Thr Thr              20      #             25      #             30 Leu Arg Gly His Met Thr Ser Val Ile Thr Cy #s Leu Gln Phe Glu Asp          35          #         40          #         45 Asn Tyr Val Ile Thr Gly Ala Asp Asp Lys Me #t Ile Arg Val Tyr Asp      50              #     55              #     60 <210> SEQ ID NO 21 <211> LENGTH: 43 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 21 Val Arg Ile Lys Gln His Ile Val Ser Thr Tr #p Ala Glu His Thr Gly   1               5  #                 10  #                 15 Glu Val Cys Gly Leu Ser Tyr Lys Ser Asp Gl #y Leu Gln Leu Ala Ser              20      #             25      #             30 Gly Gly Asn Asp Asn Thr Val Met Ile Trp As #p          35          #         40 <210> SEQ ID NO 22 <211> LENGTH: 43 <212> TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE: 22 Val Arg Val Ala Glu His His Val Ala Thr Le #u Ser Gly His Ser Gln   1               5  #                 10  #                 15 Glu Val Cys Gly Leu Arg Trp Ala Pro Asp Gl #y Arg His Leu Ala Ser              20      #             25      #             30 Gly Gly Asn Asp Asn Leu Val Asn Val Trp Pr #o          35          #         40 <210> SEQ ID NO 23 <211> LENGTH: 41 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 23 Ser Ile Asn Lys Lys Phe Leu Leu Gln Leu Se #r Gly His Asp Gly Gly   1               5  #                 10  #                 15 Val Trp Ala Leu Lys Tyr Ala His Gly Gly Il #e Leu Val Ser Gly Ser              20      #             25      #             30 Thr Asp Arg Thr Val Arg Val Trp Asp          35          #         40 <210> SEQ ID NO 24 <211> LENGTH: 45 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 24 Thr Arg Thr Ser Leu Pro Gln Phe Ser Lys Ly #s Thr His Thr Ala Ala   1               5  #                 10  #                 15 Val Lys Ala Leu Ser Trp Cys Pro Tyr Ser Pr #o Asn Ile Asn Asn Ser              20      #             25      #             30 Gly Gly Gly Gln Thr Asp Lys His Ile His Ph #e Trp Asn          35          #         40          #         45 <210> SEQ ID NO 25 <211> LENGTH: 49 <212> TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE: 25 Ser Ala Pro Gly Glu Gly Gly Trp Val Pro Le #u Gln Thr Phe Thr Gln   1               5  #                 10  #                 15 His Gln Gly Ala Val Lys Ala Val Ala Trp Cy #s Pro Trp Gln Ser Asn              20      #             25      #             30 Val Leu Ala Thr Gly Gly Gly Thr Ser Asp Ar #g His Ile Arg Ile Trp          35          #         40          #         45 Asn <210> SEQ ID NO 26 <211> LENGTH: 44 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 26 Ile Lys Lys Gly Cys Cys Thr His Val Phe Gl #u Gly His Asn Ser Thr   1               5  #                 10  #                 15 Val Arg Cys Leu Asp Ile Val Glu Tyr Lys As #n Ile Lys Tyr Ile Val              20      #             25      #             30 Thr Gly Ser Arg Asp Asn Thr Leu His Val Tr #p Lys          35          #         40 <210> SEQ ID NO 27 <211> LENGTH: 21 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 27 Ser Ile Thr Gly Ala Arg Val Gly Ser Ile As #n Thr Gly Ser Gln Val   1               5  #                 10  #                 15 Ser Ser Leu His Trp              20 <210> SEQ ID NO 28 <211> LENGTH: 43 <212> TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE: 28 Val Cys Ser Gly Ala Cys Leu Ser Ala Val As #p Ala His Ser Gln Val   1               5  #                 10  #                 15 Cys Ser Ile Leu Trp Ser Pro His Tyr Lys Gl #u Leu Ile Ser Gly His              20      #             25      #             30 Gly Phe Ala Gln Asn Gln Leu Val Ile Trp Ly #s          35          #         40 <210> SEQ ID NO 29 <211> LENGTH: 63 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 29 Leu Pro Lys Glu Ser Ser Val Pro Asp His Gl #y Glu Glu His Asp Tyr   1               5  #                 10  #                 15 Pro Leu Val Phe His Thr Pro Glu Glu Asn Pr #o Tyr Phe Val Gly Val              20      #             25      #             30 Leu Arg Gly His Met Ala Ser Val Arg Thr Va #l Ser Gly His Gly Asn          35          #         40          #         45 Ile Val Val Ser Gly Ser Tyr Asp Asn Thr Le #u Ile Val Trp Asp      50              #     55              #     60 <210> SEQ ID NO 30 <211> LENGTH: 42 <212> TYPE: PRT <213> ORGANISM: Homo sapiens <400> SEQUENCE: 30 Tyr Pro Thr Met Ala Lys Val Ala Glu Leu Ly #s Gly His Thr Ser Arg   1               5  #                 10  #                 15 Val Leu Ser Leu Thr Met Ser Pro Asp Gly Al #a Thr Val Ala Ser Ala              20      #             25      #             30 Ala Ala Asp Glu Thr Leu Arg Leu Trp Arg          35          #         40 <210> SEQ ID NO 31 <211> LENGTH: 42 <212> TYPE: PRT <213> ORGANISM: Saccharomyces cerevisiae <400> SEQUENCE: 31 Val Ala Gln Met Lys Cys Leu Tyr Ile Leu Se #r Gly His Thr Asp Arg   1               5  #                 10  #                 15 Ile Tyr Ser Thr Ile Tyr Asp His Glu Arg Ly #s Arg Cys Ile Ser Ala              20      #             25      #             30 Ser Met Asp Thr Thr Ile Arg Ile Trp Asp          35          #         40 

What is claimed is:
 1. An antibody that specifically binds a polypeptide selected from: a) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 2 or a fragment thereof; b) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 4 or a fragment thereof; and c) a polypeptide encoded by a first nucleotide sequence, wherein the first nucleotide sequence hybridizes to the complement of a second nucleotide sequence at 42° C. in 40% formamide and 5×SSPE followed by three washes in 2×SSC, 0.1% SDS at 50° C. and one wash in 0.5×SSC, 0.1% SDS, wherein the second nucleotide sequence is SEQ ID NO: 1 or SEQ ID NO: 3; wherein the polypeptide forms a complex having cell cycle dependent kinase activity against at least histone H1 alpha-casein, and myelin basic protein.
 2. An antibody of claim 1 which is a monoclonal antibody. 